Shake Well Before Dispensing

Kate Kelly, PharmD

Published Online: Saturday, October 1, 2005

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Obviously, it is important to ensure
that the active ingredient(s) in a suspension
is (are) properly dispersed
throughout the vehicle before administration.
"Shake well before use" is a
common reminder (in the form of
directions typed on the pharmacy
label, an auxiliary label, or verbal
instructions) given by pharmacists to
patients who receive oral suspensions.
Yet, how often is this important
reminder forgotten by pharmacy staff
members when preparing a smaller
quantity of a suspension from a large
stock bottle? What happens if the
stock bottle is not shaken or is inadequately
shaken?

One mother knows all too well. In a
report to the Institute for Safe Medication
Practices, she explained that her
son had been diagnosed with epilepsy,
and his seizures were well controlled
with carbamazepine (Tegretol) oral suspension.
His prescription called for 8 oz
of carbamazepine to be dispensed with
each refill. Because the medication is
available in a 16-oz stock bottle, smaller
bottles were prepared for each refill.

Several days after starting a new bottle,
the son had a recurrence of
seizures that lasted about a week. During
this time, his mother noticed that
the suspension had a different appearance
from the previous prescription.
She mentioned this difference to the
prescribing physician, who recommended
getting a new refill. She was
subsequently more aware of the
appearance of the suspension whenever
she had the medication refilled.
Whenever the suspension looked different
from what was expected, she
would ask the pharmacist for a
replacement, dispensed from an
unopened manufacturer's bottle and
shaken in her presence.

After a few of these occurrences,
however, she insisted that the pediatrician
write prescriptions instructing
pharmacists to dispense the medication
only in the 16-oz unopened manufacturer's
stock bottle. She saved several
of the more suspicious-looking
suspensions dispensed in 8-oz bottles
and sent them to the manufacturer.
Assays performed by the manufacturer's
Quality Control Division revealed
that 3 of the bottles contained suspensions
that were significantly less concentrated
than the expected 100-mg/5-mL concentration, and 1 bottle
of suspension was 3 times more concentrated
than was expected!

The problem appears to have
stemmed from pharmacy staff members
not shaking or inadequately shaking
the stock bottle of carbamazepine
suspension before preparing the smaller
bottle. If an unopened stock bottle
of a suspension was inadequately
shaken before preparing a smaller bottle,
the suspension that was poured
out could potentially be less concentrated
than expected. The remainder
of the stock suspension would then be
more highly concentrated. Both situations
could potentially lead to significant
variability in doses, which could
affect disease control (ie, recurrence of
seizures resulting from the less-concentrated
carbamazepine suspension
dispensed). This variability is particularly
significant for drugs with a narrow
therapeutic index. Even if the suspension
is adequately shaken prior to
dispensing, if patients do not shake
the medication properly, similar variability
in doses can occur.

In order to prevent such problems,
pharmacy staff members should be
sure to adequately shake all suspensions.
Education may be required for
pharmacy technicians and students,
who may not be aware of the difference
between a solution and a suspension.
Visually check that the suspension
is uniformly dispersed before it is
transferred from its original container.
Pharmacists involved in the final
check of a suspension should verify
with the individual who prepared it
that this important step was performed
before allowing the suspension
to be dispensed.

Consider making auxiliary labels as
reminders for pharmacy staff members that
read "Shake well before dispensing," and add
them to appropriate pharmacy stock bottles. In
addition, attention could be drawn to suspensions
by highlighting or circling the word "suspension"
on product labels. Make sure that
patients receiving suspension preparations are
counseled so that they fully understand the
need to shake the medication well before each
use. The "Shake Well" auxiliary label, which
commonly accompanies the pharmacy label on
suspension preparations being dispensed, could
easily be overlooked. It should not be used as
the only means of communicating this important
information, but rather it should serve as a
reminder for patients.

The reports described here were received
through the USP Medication Errors Reporting
Program, which is presented in cooperation
with the Institute for Safe Medication Practices
(ISMP). ISMP is a nonprofit organization
whose mission is to understand the causes of
medication errors and to provide time-critical
error-reduction strategies to the health care
community, policy makers, and the public.
Throughout this series, the underlying system
causes of medication errors will be presented
to help readers identify system changes that
can strengthen the safety of their operation.

If you have encountered medication
errors and would like to report them, you
may call ISMP at 800-324-5723 (800-
FAILSAFE) or USP at 800-233-7767 (800-23-ERROR). ISMP's Web address is www.ismp.org.

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